A piece by Jonathan Alter in The Washington Monthly, deploying political science as well as the author's own experience and insights to speculate on the reasons why the Obama administration has been largely free of scandal. Also included is a quick tour of scandals of past administrations (remember Anne Burford? I didn't think so). One scandal that, on a fast reading of the piece, I didn't see mentioned is the substandard-facilities-at-Walter-Reed story -- but I'm pretty sure that broke under G.W. Bush not Obama, so it doesn't undercut the premise.
P.s. Of course there are those on both left and right who consider some administration policies to be criminal (e.g., use of drones, targeted assassinations) or unconstitutional (or what have you), but that's not what this is about.